Humans evolved in western Africa and, over the course of tens of thousands of years, expanded across Earth. In this book, the author looks at how physical aspects of the planet shaped these events. I’ll give you a hint. If this were a murder mystery, I’d call this a spoiler, but it’s not, so I think it’s all right. A large part of humanity’s activities were shaped by… plate tectonics. As everyone probably knows, the shapes and relative positions of Earth’s continents slowly shift as the plates they rest on float on a subterranean sea of molten rock. This movement creates rift valleys and mountains and seas. Together with the shape of Earth’s orbit and its tilt to the plane of the ecliptic, which has a major influence on the climate, we have pretty much all aspects of the playing board for life’s evolutionary game. It determines what any species can be or do. Humanity is no exception. So, the fact that we thrive where there is potable water and fertile soil, tend to avoid deserts, and have difficulty crossing high mountains or wide oceans, all comes down to plate tectonics. Not so surprising, I suppose, but what’s kind of neat about this book is that goes on to offer a bit of explanation for things like how oil and minerals got to where people could get to them, and why the trade winds blow, and who hasn’t wondered about such things?